1. Technical Field of the Invention
The invention relates generally to communication systems; and more particularly, it relates to managing and directing the links of communication between various devices within such communication systems.
2. Description of Related Art
Data communication systems have been under continual development for many years. One typical type of communication systems that has been receiving increased attention over the past several years are those involving Local Area Networks (LANs). One variant of a LAN is a Wireless LAN (WLAN). A WLAN employs wireless communication between the various devices within the WLAN. There has been a great deal of energy devoted to developing ways to improve the manner in which devices within WLANs interact. There has been a variety of directions in which this development energy has been directed. For example, some efforts are focused on the seeking to improve the type of signaling used between the various WLAN interactive devices. Other efforts have focused on the development on trying to minimize the complexity of the hardware included within the WLAN interactive devices while maintaining at least a minimum standard of performance. Some other avenues of development have sought to try to increase the overall throughput of the WLAN; this can be especially of concern when subscribers of the WLAN are seeking to access an external Wide Area Network (WAN), and the WLAN itself undesirably acts as a bottleneck to those subscribers. In addition, many other areas of development have also received attention in the past years.
More specifically referring to one avenue of development, the Institute of Electrical & Electronics Engineers (IEEE) 802.11 specification has been under continual development in an effort to try to improve the way in which WLANs operate. In this particular effort, there have been a number of revisions to the IEEE 802.11 specification draft, including the commonly known 802.11b specification and the newer revision to that draft, namely, the 802.11g specification draft. The 802.11g specification is backward compatible with the 802.11b specification, so that legacy devices within the WLAN can still interact with the WLAN, although probably using a reduced functionality set.
There are typically two manners in which to implement a WLAN: ad hoc (shown in FIG. 1) and infrastructure (shown in FIG. 2).
FIG. 1 is a system diagram illustrating a prior art ad hoc Wireless Local Area Network (WLAN). Referring to FIG. 1, the ad hoc implementation employs a number of WLAN interactive devices that is typically operable to communicate with each of the other WLAN interactive devices within the WLAN. There is oftentimes no structure to the network. In some instances, one of the WLAN interactive devices is designated as a master of the network and the other WLAN interactive devices operate as slaves to that master.
FIG. 2 is a system diagram illustrating a prior art infrastructure/multiple Access Point (AP) WLAN. Referring now to the FIG. 2, in the infrastructure (or multiple Access Point (AP)) implementation WLAN, a number of APs are employed to support communication with the WLAN interactive devices (which are sometimes referred to as wireless stations (STAs) in the infrastructure implementation). This infrastructure architecture uses fixed network APs with which the STAs can communicate. These network APs are sometimes connected to landlines (that may be connected to one or more WANs, as described above) to widen the LAN's capability by bridging wireless nodes to other wired nodes. If service areas overlap, handoffs can occur. This infrastructure structure may be implemented in a manner that is analogous to the present day cellular networks around the world.
Considering the development of the 802.11 specification and the subsequent generations and/or versions therein (e.g., 802.11b and 802.11g), there can sometimes be difficulty when various STAs and/or APs within the WLAN support both functionality sets. For example, there may be some instances where an AP or STA is only 802.11b operable. Alternatively, there may be some instances where an AP or STA is 802.11g operable; again, it is noted that the devices supporting the 802.11g functionality set are also typically backward compatible with the 802.11b functionality set. In one instance, when a 802.11g device associated a the WLAN via an 802.11b operable AP, then the full and improved functionality of the 802.11g specification, compared to the 802.11b specification, will not be fully capitalized. Moreover, it has found that the mixing of 802.11b and 802.11g devices within a single WLAN can severely reduce the overall throughput of the entire WLAN. As briefly mentioned above, this can be extremely problematic when STAs within the WLAN are using the WLAN to access an external WAN, such as the Internet. Even is a user has a fully operable 802.11g device, if that 802.11g user associates with the WLAN via an 802.11b operable AP, then that user will not capitalize fully on the 802.11g functionality of his/her device.
Moreover, the complexity and problems introduced by the mixing of 802.11b and 802.11g users within a WLAN becomes even more exacerbated given the fact that the 802.11b and 802.11g specifications employ two different modulation types. In the 2.4 GHz (Giga-Hertz) bands, there are two standards for modulation to achieve the various data rates. The older standard is 802.11b. It occupied three channels (of approximately 22 MHz (Mega-Hertz) spread) that are adjacent in the 2.4 GHz band. The 802.11b specification employs Complementary Code Keying (CCK) modulation; in contrast, the 802.11g specification employs Orthogonal Frequency Division Multiplexing (OFDM) modulation. Moreover, the newer 802.11g standard occupies the same band while using the OFDM modulation to achieve data rates approaching 54 Mbps (Mega bits per second). One of the many problems that may arise in this situation is that the 802.11b clients never expect to see OFDM modulation from the 802.11g uses in that particular channel. So if a mixed 802.11b and 802.11g community of users (which a mixed WLAN) starts transmitting in the same channels at the same time, then the performance of the WLAN will not be anywhere as near as good as if the community of users were homogenous as being all 802.11b or 802.11g users.
However, if an approach were made to allow only 802.11b (or only 802.11g) users within a WLAN, then the backward capability of the 802.11g users would be worthless and the 802.11b users could never interact within a WLAN where 802.11g was the chosen version of the 802.11 specification to be implemented. This represents a dilemma within the continued development of WLANs, in that, users of varied functionality devices may be implemented therein. The prior art does not present an adequate and efficient solution to address such deficiencies within WLAN implementation.